1. Field of the Invention
The present invention relates to vulcanizates of hydrogenated nitrile rubber having improved properties, especially one or more of improved load bearing capabilities, improved abrasion resistance and reduced heat build-up.
2. Description of the Prior Art
Published European Patent Application 319320A teaches rubber compositions which contain hydrogenated nitrile rubber and an unsaturated carboxylic metal salt--more specifically, the unsaturated carboxylic metal salt is a metal salt (magnesium, calcium, zinc and aluminum being preferred) of an unsaturated carboxylic acid having one or more carboxylic groups. Such unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and the like. The amount of unsaturated carboxylic metal salt, per 100 parts by weight of the hydrogenated nitrile rubber, is from 1 to 100, preferably from 5 to 40, parts by weight.
U.S. Pat. No. 4,843,114 teaches compounds for tracked vehicle pads comprising 100 parts by weight of hydrogenated nitrile rubber, from 1.5 to 30 parts by weight of zinc oxide or magnesium oxide, from 25 to 50 parts by weight of zinc methylmethacrylate or zinc dimethylmethacrylate, a curative selected from dicumyl peroxide and sulfur or sulfur compounds, a filler and antidegradant systems.
U.S. Pat. No. 4,857,571 teaches that prevulcanization (i.e. scorch) of an elastomer is inhibited by using a formulation containing a free radical curable elastomer, a free radical source, a polyfunctional monomer coagent capable of reacting with the free radicals to crosslink the elastomer, and a vulcanization inhibitor selected from certain methyl-substituted-aminoalkyl phenols, in which the elastomer is selected from a long list of polymers which does not include hydrogenated nitrile rubber and in which the polyfunctional monomer coagent includes a long list of materials including zinc di-acrylate and zinc dimethacrylate.
U.S. Pat. No. 4,918,144 teaches a vulcanizable composition containing 100 parts by weight of hydrogenated nitrile rubber, 0.2 to 10 parts by weight of an organic peroxide and 5 to 90 parts by weight of zinc dimethacrylate.
U.S. Pat. No. 4,983,678 teaches a curable composition containing 100 parts by weight of a rubber mixture containing 60 to 90 weight per cent of a hydrogenated nitrile rubber and 10 to 40 weight per cent of an ethylene-propylene copolymer rubber, 10 to 100 parts by weight of the zinc salt of methacrylic acid and 0.2 to 10 parts by weight of an organic peroxide.
U.S. Pat. No. 4,990,570 teaches a curable composition containing 100 parts by weight of a hydrogenated nitrile rubber, 10 to 100 parts by weight of the zinc salt of methacrylic acid, 5 to 50 parts by weight of silicic anhydride and 0.2 to 10 parts by weight of an organic peroxide.